This study is based on oribatid mite materials collected from the vicinities of Phatthaya city and the Samet Island in Thailand; 18 species from 14 genera and 11 families are registered, of these, nine species are recorded from the Thai fauna for the first time. A new species of the genus Dolicheremaeus (Otocepheidae) – D. phatthayaensis sp. n. – is described. The supplementary description of Galumna paracalcicola Ermilov et Anichkin, 2014 is presented based on specimens from Thailand. Identification keys to the known representatives of the genera Dolicheremaeus from Thailand and Galumna from the Oriental region are presented. Galumna indica Hafeez Kardar, 1989 and G. striata Hafeez Kardar, 1989 are combined in the genus Setogalumna.